The present invention relates to a method and apparatus for manufacturing inseparable assemblies. More specifically, the invention relates to molded inseparable assemblies.
Inseparable assemblies are frequently used in the construction of mechanical devices. Particularly in machines with rotating or reciprocating components or assemblies prone to have severe machine vibrations, the use of inseparable assemblies is essential to avoid loosening of fasteners and separation of assemblies. This problem is exacerbated where the assemblies need to have relative motion among their components while maintaining their integrity. Examples of such include hinges and socket joints.
The manufacture of inseparable assemblies is well known. Typically the individual components that comprise the assembly are first manufactured by any suitable currently available method. These components are then combined into an inseparable assembly by any of a number of available methods. For example the components may be welded or peened together. Alternately the components may be adhered by adhesives or shrunk fit by the heat/freeze method. The assembly and securing of these components inherently increases the assembly cost and problems with the integrity of the securing means may be experienced, such as insufficient shrink or peening or defective welds.
The use of molding processes to manufacture components dates back to ancient history. Egyptians poured molten metals into forms which when cooled created items with shapes mirroring the forms. In the process of molding metals, a two piece form or mold is produced with a hollow interior having a shape mimicking the shape of the exterior of the piece to be molded. Molten metal is poured into the mold and the metal fills the hollow interior. The two pieces of the mold are separated from each other and the newly poured piece is removed.
Similar molding processes have existed for some time for manufacturing components from plastic materials. The most common of these processes is injection molding. Typically in this process the mold is housed in a machine which operates like a press and can be either mechanically or hydraulically actuated. As earlier described, the mold with a reverse image of the part is made in two pieces which when aligned together have an interior shape conforming to the shape of the component to be manufactured, and when separated permit removal of the part. Plastic pellets enter a chamber of the press and are compressed by the extending press ram into a liquid form. The liquid plastic material is fed through passageways into the interior of the mold where it solidifies. The press ram then retracts and the two pieces of the mold separate permitting removal of the newly formed plastic part.
The following disclosures may be relevant to various aspects of the present invention:
U.S. Pat. No. 4,649,068,
Patentee: Collette
Issue Date: Mar. 10, 1987
U.S. Pat. No. 4,578,028
Patentee: Dirksing et al
Issue Date: Mar. 25,1987
U.S. Pat. No. 4,153,303
Patentee: Tanner
Issue Date: May 8, 1979
U.S. Pat. No. 4,046,444
Patentee: Brorein
Issue Date: Sep. 6, 1977
U.S. Pat. No. 3,911,528
Patentee: Rojic, Jr.
Issue Date: Oct. 14, 1975
U.S. Pat. No. 3,891,171
Patentee: Samuelian et al.
Issue Date: Jul. 12, 1977
The relevant portions of the foregoing disclosures may be briefly summarized as follows:
U.S. Pat. No. 4,649,068 discloses an injection molded preform that is intended to be used in a blow molded container. The remainder of the container is molded around the preform which serves to reinforce the neck of the container.
U.S. Pat. No. 4,578,028 discloses a core pin that is used in connection with a blow molded container. The body portion of the container is molded with the core pin. The pin serves to support the neck of the container.
U.S. Pat. No. 4,153,303 discloses a multipart plastic hub assembly. The assembly includes a pair of symmetrically shaped hub members. A rubber tire portion fits around the perimeter of the hub. The pieces snap together with the assistance of detents.
U.S. Pat. No. 4,046,444 discloses a plastic shrouded electrical connector. The connector includes two plastic components that interlock about the metal connector to form an insulated barrier for the connector.
U.S. Pat. No. 3,911,528 discloses a metal hinge that is constructed from two flat components that have mating parallel fingers that are in a position angled to the axis of the hinge. The fingers are coiled together to form an interlocking pivoting hinge.
U.S. Pat. No. 3,891,171 discloses an adjusting cam mechanism for accommodating a variety of mixing bowls for an electric mixer. The mechanism includes interconnected components that have relative motion.
In accordance with one aspect of the present invention, there is provided a method for movably connecting two members. The method comprises the steps of molding a first member in a first mold portion and placing the first member within a second mold portion. The method also includes inserting molten material into the second mold portion to form a second member. The method further includes limiting contact between the first member and the material to prevent bonding between the first member and to permit relative motion between the members. The method also includes cooling the molten material into a solid form, whereby an assembly is formed from the first and the second member. The method further includes removing the members from the second mold assembly.
In accordance with another aspect of the present invention, there is provided a hinge assembly, comprising a first member and a second member integrally molded with the first member to be inseparably interconnected therewith and movable relative thereto.